Hoelemann, Jens A. and Henrich, Ruediger (1994): Allochthonous versus autochthonous organic matter in Cenozoic sediments of the Norwegian Sea; evidence for the onset of glaciations in the Northern Hemisphere

Leg/Site/Hole:
ODP 104
Identifier:
1994-054612
georefid

Creator:
Hoelemann, Jens A.
GEOMAR, Research Center for Marine Geosciences, Kiel, Federal Republic of Germany
author

Henrich, Ruediger
Universitaet Bremen, Federal Republic of Germany
author

Identification:
Allochthonous versus autochthonous organic matter in Cenozoic sediments of the Norwegian Sea; evidence for the onset of glaciations in the Northern Hemisphere
1994
In: Schaefer, P. (prefacer), Bleil, U. (prefacer), Norwegian-Greenland Sea
Elsevier, Amsterdam, Netherlands
121
1-2
87-103
The Cenozoic sediments sampled in ODP Leg 104 on the Voring Plateau show a distinct variability of the total organic carbon content (TOC) and the accumulation rates of TOC. Based on the geochemical and organic-petrographic characterization of the sedimentary organic matter (OM), the allochthonous and autochthonous proportion of the OM could be quantified. The results clearly demonstrate that high TOC percentages and TOC accumulation rates in Cenozoic sediment sections display a generally high input of allochthonous organic matter. Oxidized and partly well-rounded organic particles built up the main portion of OM within the Miocene, TOC-rich sediments. The most probable source of this oxidized OM are reworked sediments from the Scandinavian shelf. Changes in the input of these organic particles are to some degree correlative with sea-level changes. The Cenozoic accumulation of autochthonous OM is low and does not reveal a clear variation during the Miocene and early Pliocene. In spite of a high accumulation rate of biogenic opal during the Early Miocene, the accumulation rate of autochthonous TOC is low. The autochthonous particle assemblage is dominated by relatively inert OM, like dinoflagellate cysts. This points to an intensive biological and/or early diagenetic degradation of the marine OM under well oxidized bottom water conditions during the last 23 Myr. Nevertheless, a continuation of marine OM degradation during later stages of diagenesis cannot be excluded. A prominent dominance of allochthonous OM over autochthonous is documented with the beginning of the Pliocene. At 2.45 Ma the episodic occurrence of ice-rafted, thermally mature OM reflects the onset of the glacial erosion of Mesozoic, coal and black shale bearing sediments on the Scandinavian and Barents Sea shelves. The first occurrence of these, in view of the actual burial depth, thermally overmature OM particles is, therefore, a marker for the beginning of the strong Scandinavian glaciation and the advance of the glacial front toward the shelves.
English
Coverage:Geographic coordinates:
North:71.0000
West:1.0000East: 32.0000
South:54.3000

Oceanography; Quaternary geology; Arctic Ocean; carbon; Cenozoic; continental shelf; Europe; glacial sedimentation; glaciation; glaciomarine sedimentation; ice movement; Leg 104; marine sedimentation; marine sediments; Neogene; Norwegian Sea; Ocean Drilling Program; organic carbon; organic compounds; organic materials; paleoclimatology; Pliocene; provenance; Quaternary; Scandinavia; sedimentation; sedimentation rates; sediments; Tertiary; Voring Plateau; Western Europe;

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